KANSAS CITY, Mo. (AP) Andy Reid has been preparing for preseason games as a head coach for nearly two decades.

Kyle Shanahan is doing it for the first time.

Yet the new 49ers coach has a clear picture of how his debut will go Friday night in Kansas City, when he matches wits with Reid and the Chiefs in a game that offers a bit more intrigue than usual.

"To be honest with you it's miserable for a coach," Shanahan said. "You never want to go out and look bad and get embarrassed. But I also am very well aware that any play that works in the preseason will not work in the regular season. So you don't want to waste anything either.

"There's a fine line between that," he explained. "You can feel good going 4-0 in the preseason, and I've done that before and lost the first game, and no one cares what the preseason record was. We also want to do good, too, as everyone does. So that's the inner turmoil you're constantly battling as a coach."

"Obviously the quarterbacks have a little more responsibility with it, just with all the calls and so on," Reid said, "but just the main thing is to go execute."

Here are some of the more fascinating things to watch for when the 49ers and Chiefs meet:

THE NEW COACHES: Yes, Shanahan has been an offensive coordinator for several franchises, but this is the 37-year-old's first chance to call the shots. It's also the first opportunity for his coaching staff to work together in a game-like setting.

QUARTERBACK COMPETITION: Brian Hoyer will get the start for San Francisco and Alex Smith will start for Kansas City, and neither veteran is getting much pressure at this point. But that doesn't mean there isn't a whole lot of competition for the guys barking at their heels.

Matt Barkley will be the first off the bench for San Francisco, but Shanahan said "we'll see how that goes in the second game." In other words, there's a good chance that rookie C.J. Beathard - who has looked good throughout training camp - will be first on deck with a good performance in Kansas City.

Smith will give way to Chiefs veteran Tyler Bray in the second quarter, while first-round draft pick Patrick Mahomes II gets the third quarter. Those two are in a spirited battle for the backup job.

"They've put in a lot of work, Tyler in particular," Chiefs offensive coordinator Matt Nagy said, "and he's done a really good job at mentally getting into it. He's had some opportunities in preseason, so I know he's really looking forward to just coming out here and trying to do the best he can."

TASTY REUBEN: The 49ers are salivating at the thought of insider linebacker Reuben Foster playing alongside NaVorro Bowman. But whether that happens Friday night is questionable after the former Alabama standout was hobbled by an ankle injury in practice this week.

"His ankle has been bothering him a little each day," Shanahan said after Wednesday's workout. "It looked like he kind of did the same thing, just kind of got stepped on a little bit."

SPEAKING OF INJURIES: Rookie tight end George Kittle is unlikely to play for San Francisco with a hamstring injury, while offensive lineman Joshua Garrett is out for a month after knee surgery.